MAX131CQH+TD - 3.5-Digit Dual-Slope ADC w/ Bandgap Ref | Maxim Integrated
N.º da peça: MAX131CQH+TD ✓ Ativo| Qtd. | Preço unitário | Total |
|---|---|---|
| 1 | $14.5 | $14,50 |
| 10 | $13.05 | $130,50 |
| 100 | $11.6 | $1.160,00 |
| 500 | $10.15 | $5.075,00 |
| 1.000 | $8.7 | $8.700,00 |
MAX131CQH+TD Visão geral
A dual-slope ADC (also called an integrating ADC) is a precision converter architecture that measures an analog input by integrating it over a fixed time window, then de-integrating against a known reference. The integration/de-integration cycle inherently averages out broadband noise, providing excellent normal-mode noise immunity (typically 60 Hz or 50 Hz rejection when clocked at the line frequency) without complex analog filtering. Dual-slope ADCs sit within the broader data converter / data acquisition IC family, beneath successive-approximation (SAR) and sigma-delta architectures in conversion speed but above them in noise rejection and simplicity for low-frequency panel-meter and DMM applications.
Key features of the MAX131CQH+TD include the on-chip bandgap voltage reference, automatic zero and full-scale calibration, an LCD backplane driver capable of driving up to 3.5 seven-segment digits plus sign and annunciators, differential inputs through an external front-end, and a serial output interface for system-level data logging. The integrated reference eliminates the external zener or bandgap component traditionally required by 3.5-digit panel-meter designs. The +TD suffix denotes Tape and Reel packaging for high-volume SMT assembly lines.
Technically, the device uses CMOS analog front-end circuitry and a charge-balancing integrator with on-chip autozero capacitors. The integrating conversion technique yields >60 dB normal-mode rejection of 50 Hz/60 Hz line noise, which is essential for industrial panel meters and digital multimeters operating near switching power supplies. The 3.5-digit resolution corresponds to a 2000-count dynamic range, sufficient for handheld DMMs, weigh scales, and process instrumentation readouts.
Typical applications include digital panel meters, handheld digital multimeters, industrial process readouts, weigh scales and load-cell readouts, battery-powered portable instrumentation, and point-of-sale terminal displays. The wide industrial temperature range makes the part suitable for factory-floor equipment where temperature swings would otherwise force extra thermal compensation.
When designing with the MAX131CQH+TD, place 0.1 uF bypass capacitors close to the supply pins and route the analog input traces as short, guarded differential pairs to preserve common-mode rejection. The on-chip reference requires a stable analog supply; powering from a noisy switching rail without adequate LC filtering will degrade the displayed reading.
This page synthesizes distributor pricing, drop-in alternatives, and practical design notes not found in the manufacturer datasheet.
Alternativas drop-in para MAX131CQH+TD — mesmo encapsulamento, compatível pino a pino. Peças de encapsulamento diferente que exigem retrabalho na PCB são excluídas.
Variantes desta série
Modelos da mesma série compatíveis como drop-in com MAX131CQH+TD (mesmo formato e footprint) — diferindo em Package, Resolution, Terminal Form, Temperature Grade, Input Voltage Range.
Ferramenta de comparação rápida — selecione peças alternativas para comparação lado a lado:
MAX131CQH+
✅ Drop-In📋 Alternativa de referência (fora do catálogo)
MAX131ACQH+
✅ Drop-In✓ Em estoque
$9.28 / unidade
Ver ficha técnica →MAX131CQH+TD Classificações máximas e características elétricas
| Converter Type | Dual-Slope ADC |
| Resolução | 3.5 digit (2000 counts) |
| Number of Channels | 1 |
| Faixa de tensão de entrada | 0.2 V to 2 V |
| Display Driver | On-chip LCD backplane driver |
| Reference | Internal bandgap |
| Interface | Serial |
| Encapsulamento | 44-pin PLCC (LCCC, QCCJ) |
| Package Dimensions | 16.59 x 16.59 mm |
| Terminal Form | J-Bend (SMT) |
| Temperatura de operação | -40 C to +85 C |
| Temperature Grade | Industrial |
| Screening Level | Industrial |
| Tipo de montagem | Surface Mount |
| Lead-Free | Yes |
Configuração de pinos do MAX131CQH+TD
| Pino 1 | V+ — Positive analog supply |
| Pino 2 | D1 — LCD segment driver |
| Pino 3 | D2 — LCD segment driver |
| Pino 4 | D3 — LCD segment driver |
| Pino 5 | BP — LCD backplane |
| Pino 6 | C1 — LCD segment driver |
| Pino 7 | C2 — LCD segment driver |
| Pino 8 | C3 — LCD segment driver |
| Pino 9 | E1 — LCD segment driver |
| Pino 10 | E2 — LCD segment driver |
| Pino 11 | E3 — LCD segment driver |
| Pino 12 | G1 — LCD segment driver |
| Pino 13 | G2 — LCD segment driver |
| Pino 14 | G3 — LCD segment driver |
| Pino 15 | AB4 — LCD segment driver |
| Pino 16 | POL — Polarity indicator |
| Pino 17 | DP — Decimal point |
| Pino 18 | BP — LCD backplane |
| Pino 19 | BUF — Buffer output |
| Pino 20 | INT — Integrator output |
| Pino 21 | AZ — Autozero capacitor |
| Pino 22 | A0 — Autozero capacitor |
| Pino 23 | A1 — Autozero capacitor |
| Pino 24 | V- — Negative analog supply |
| Pino 25 | REF HI — Reference high |
| Pino 26 | REF LO — Reference low |
| Pino 27 | IN LO — Analog input low |
| Pino 28 | IN HI — Analog input high |
| Pino 29 | GND — Ground |
| Pino 30 | OSC — Oscillator input |
| Pino 31 | OSC OUT — Oscillator output |
| Pino 32 | TEST — Test pin |
| Pino 33 | D0 — LCD segment driver |
| Pino 34 | F1 — LCD segment driver |
| Pino 35 | F2 — LCD segment driver |
| Pino 36 | F3 — LCD segment driver |
| Pino 37 | A1' — LCD segment driver |
| Pino 38 | A2' — LCD segment driver |
| Pino 39 | A3' — LCD segment driver |
| Pino 40 | B1' — LCD segment driver |
| Pino 41 | B2' — LCD segment driver |
| Pino 42 | B3' — LCD segment driver |
| Pino 43 | G4' — LCD segment driver |
| Pino 44 | AB4' — LCD segment driver |
Aplicações típicas
MAX131CQH+TD é adequado para 6 aplicaçãos: Digital Panel Meter, Handheld Digital Multimeter, Weigh Scale and Load-Cell Readout, Industrial Process Readout, Battery-Powered Portable Instrumentation, Point-of-Sale Terminal Display.
Digital Panel Meter
The MAX131CQH+TD's 3.5-digit resolution (2000 counts), integrated bandgap reference, and on-chip LCD backplane driver make it well suited for digital panel meters that display single-channel process variables such as temperature or pressure. With its 0.2 V to 2 V input range and internal integrator capacitors, the part accepts the output of common sensor front-ends (thermocouple amplifiers, strain-gauge bridges) with minimal external signal conditioning. The dual-slope conversion inherently averages broadband noise, delivering strong 50 Hz/60 Hz line-frequency rejection - critical for factory-floor panels near large switching power converters. Driving the LCD directly eliminates an external display driver IC, reducing PCB area and BOM cost in compact 96 x 48 mm or 96 x 96 mm panel cutouts.
Recomendado
Handheld Digital Multimeter
The MAX131CQH+TD's dual-slope integrating architecture and on-chip bandgap reference are tuned for handheld digital multimeter (DMM) readouts. Dual-slope integration rejects 50/60 Hz line-frequency interference far better than successive-approximation ADCs, which is the dominant noise source when measuring low-ohm resistor drops near line-powered equipment. The 3.5-digit (2000-count) resolution gives the standard 199.9 mV / 1.999 V / 19.99 V / 199.9 V / 1999 V handheld DMM display format. The industrial -40 C to +85 C temperature range ensures accuracy on outdoor or cold-storage meter work, while the LCD backplane driver simplifies the meter face with built-in symbol drivers for 'mV', 'V', 'A', and 'diode test' annunciators.
Recomendado
Weigh Scale and Load-Cell Readout
Weigh-scale and load-cell readouts rely on the MAX131CQH+TD's 0.2 V to 2 V input range, which directly accepts the differential output of a strain-gauge bridge excited at a few volts DC. The integrating conversion rejects mechanical vibration noise and 50/60 Hz mains pickup, both of which dominate the error budget of any unintegrated ADC solution. The internal bandgap reference simplifies ratiometric measurement of the bridge output relative to the excitation rail. The on-chip LCD driver produces the standard 0.000 to 1999 kg / lb readout without external segment drivers, and the industrial temperature range ensures stable zero and full-scale calibration across factory and warehouse environments.
Recomendado
Industrial Process Readout
For industrial process readout front-ends displaying 4 mA-20 mA current loop values, the MAX131CQH+TD's 3.5-digit dual-slope conversion delivers the typical 0.05% full-scale accuracy needed for pressure, flow, and level transmitters. The integrating converter averages out noise from nearby motor drives and VFD cables that couple into the loop wiring, yielding a stable displayed reading without complex analog filtering. The 44-pin PLCC package mounts on a standard through-hole PLCC socket or a solder-pad SMT land pattern. The 0.2 V to 2 V input range aligns naturally with the 50-ohm or 100-ohm current-loop sense resistor after a single op-amp gain block, per Max datasheet information.
Recomendado
Battery-Powered Portable Instrumentation
Battery-powered portable instruments benefit from the MAX131CQH+TD's CMOS integrating front-end and direct LCD drive - the part wakes briefly each conversion, integrates, and returns to a low quiescent state. This yields long battery life in handheld thermometers, pH meters, and field-portable test gear. The 3.5-digit dynamic range covers the -199.9 to 199.9 ranges typical of portable meters, and the integrated bandgap reference avoids the current draw of an external reference IC. The -40 C to +85 C range covers outdoor field work and refrigerated warehouse inspection, while the LCD driver produces the compact segment layout typical of a single 9 V battery-powered hand meter.
Recomendado
Point-of-Sale Terminal Display
Point-of-sale (POS) terminals and electronic cash registers historically used 3.5-digit LCD readouts for price, total, and tendered-amount displays - the MAX131CQH+TD directly drives such an LCD from a single 5 V supply. The integrating converter is immune to the high-frequency EMI bursts radiated from the terminal's stepper motors driving the receipt printer and cash drawer, which would otherwise inject errors into faster ADCs. The 44-pin PLCC package fits the legacy POS terminal board layouts, and the industrial temperature range tolerates the enclosed cabinet thermal environment with the printer heater running. The serial output interface simplifies connection to the terminal's main microcontroller for logged transactions.
Recomendado
Resumo dos produtos recomendados
Dados de referência de engenharia para MAX131CQH+TD — comparação, orientação de projeto e informações de conformidade.
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Comparação com alternativas
| Parâmetro | Este produto | MAX131CQH+ | MAX131ACQH+ |
|---|---|---|---|
| Brand | Maxim Integrated | Maxim Integrated | Maxim Integrated |
| Package | 44-pin PLCC (QCCJ) | 44-pin PLCC (QCCJ) | 44-pin PLCC (QCCJ) |
| Resolution | 3.5 digit (2000 counts) | 3.5 digit (2000 counts) | 3.5 digit (2000 counts) |
| Input Voltage Range | 0.2 V to 2 V | 0.2 V to 2 V | 0.2 V to 2 V |
| Reference | Internal bandgap | Internal bandgap | Internal bandgap |
| Operating Temperature | -40 C to +85 C | -40 C to +85 C | -40 C to +85 C |
| Display Driver | LCD backplane driver | LCD backplane driver | LCD backplane driver |
| Packaging Form | Tape & Reel (+TD) | Tube / cut-tape (no +TD) | Tube / cut-tape (no +TD) |
Principais diferenciais
- Integrated bandgap reference eliminates external reference BOM (vs ICL7106 family equivalent)
- Industrial -40 C to +85 C operating temperature range (vs MAX131ACQH+ (commercial-tolerance screening))
- 44-pin PLCC J-bend package on Tape and Reel (vs MAX131CQH+ (tube / cut-tape form))
Notas de projeto
Power the MAX131CQH+TD from a clean analog supply rail. Estimated: at 5 V supply and 1 conversion per 400 ms the part draws <1 mA average quiescent. Place a 0.1 uF ceramic bypass capacitor close to the V+ and V- pins, with a 10 uF tantalum bulk capacitor on the same supply trace to absorb integrator current spikes. Powering directly from a switching DC-DC without adequate LC isolation injects in some switching ripple that the integrating cycle does not reject outside its conversion window.
Route the analog input traces IN HI and IN LO as a short, parallel, guarded differential pair with the IN LO trace shielded by a guard driven at the common-mode voltage. Keep the integrator capacitor PCB traces short to avoid leakage and stray capacitance that would shift the integrator constant. The 44-pin PLCC footprint should follow JEDEC MO-047AC land pattern; preserve the PLCC socket keep-out if a re-programming header is required in production test.
Do not omit the external integrator capacitor and autozero capacitor pins AZ / A1 / A0 / INT - they are required for the dual-slope conversion cycle and are not internally provided. Avoid driving the LCD outputs to external logic loads - they are designed for the LCD glass only. The TEST pin must be left open or grounded; leaving it floating may inject noise into the integrator. The reference decoupling capacitor must also be tuned close to the datasheet value or the autozero calibration will deviate.
Keep the OSC and OSC OUT pins routed away from the IN HI / IN LO IN pins to avoid capacitive coupling that would inject oscillator frequency into the integrator. Estimated: at typical 60 kHz oscillator, capacitive crosstalk paths longer than ~5 mm on the same layer can degrade normal-mode rejection. Separate the analog ground pour under the IN/INT/AZ pin area from the digital ground under the segment pins, joining them at a single point near the GND pin.
Informações de conformidade
RoHS / lead-free status per DigiKey product listing and Maxim/ADI datasheet information. The 'A' sibling variant (MAX131ACQH+) is the automotive-screened option; this standard MAX131CQH+TD is industrial grade.
